Shayler, Hannah A.; Siver, Peter A.

Abstract

The diatom Brachysira gravida Shayler & Siver sp. nov.is described from an oligotrophic, acidic, freshwater lake in the Ocala National Forest in north-central Florida, U.S.A. The richness of Brachysira was previously investigated to reveal that the genus is both abundant and morphologically diverse in this region of Florida and is therefore of particular taxonomic interest. Valves of Brachysira gravida are elliptical-rhombic with a swollen and rounded mid-region, concave margins that are not straight, and protracted rostrate apices. The combination of valve shape and size easily distinguish B. gravida as a distinct species, and provides a designation for several specimens previously published by other authors that could not be conclusively identified. Even though the new species has only been observed in one pond and from a nearby fossil deposit, it supports the concept that a relatively large number of unique and potentially endemic species of siliceous algae exist in the Ocala National Forest.